Treatment of hydrocarbons to produce a jet fuel and high octane gasoline



Sept. 8, 1964 R. A. WOODLE 3,148,136

TREATMENT OF HYDROCARBONS TO PRODUCE A JET v FUEL AND HIGH OCTANEGASOLINE Filed Sept. 14, 1959 United States Patent 3,148,136 TREATMENT(3F EDRUtZARBQNS T0 PRGDUCE A JET FUEL AND HEGH UQTANE GAStELiNE RobertA. Woodie, Nederianrl, Tex assignor to Texaco Inc, New York, FLY acorporation of Delaware Filed Sept. 14, 1959, Ser. No. 339,646 5 Claims.(Cl. Z08-69) This invention relates to the treatment of hydrocarbons.More particularly it is concerned with the production of improved fuelsfor gas turbine engines especially those used in the propulsion ofaircraft.

Two of the problems currently encountered in the operation of jetaircraft, as gas turbine propelled aircraft are commonly called, arethat the fuels currently employed produce excessive smoke during takeoffand the highly luminous flame produced by the burning of the fuel makesfrequent engine overhauls necessary. To prevent or reduce the productionof smoke during take-ofl it is customary to inject a water-alcoholmixture into the engine with the fuel during take-off. This procedurerequires a dual tankage system in the aircraft and is an expensivesolution to the problem of reducing or eliminating smoke. Furthermore,it is an added complication at a critical moment in the operation of theaircraft. Also, because the fuels currently used burn with highlyluminous flames which radiate large amounts of heat, it is necessary toinspect and overhaul the gas turbine engine after from about 500-600hours of operation. Those parts in close proximity to the flame,particularly the flame tube which surrounds the combustion zone having atemperature of 3000 F. and higher, are subjected to extreme thermalstress which results in creeping, warping and buckling of the flame tubeand other par-ts. In some instances the high radiation from the flamealso causes buckling of the turbine rotor to such an extent thatmalfunctioning and sometimes complete failure of the engine results.

It has been found that fuels having a high luminosity number have areduced tendency to produce smoke during take-off and also tend to burnwith a flame of low radiation. Hence, when high luminosity number fuelsare used, the engine parts are subjected to less thermal stress than inthe case of fuels currently in use such as JP-4, J P-5 and kerosenewhich have luminosity numbers of about 54, 37 and 36 respectively. Thepresent invention contemplates the production of fuels having luminositynumbers ranging from 85100 and higher.

It is therefore an object of the present invention to provide a highluminosity number fuel for gas turbine or jet engines.

Another object of the invention is to provide a jet fuel which subjectsthe jet engine parts to reduced thermal stress.

Another object of the invention is to provide an improved process forthe production of jet fuels which produce reduced amounts of smokeduring take-off. These and other objects will be obvious from thefollowing disclosure.

' The luminosity number which is used to rate gas turbine engine fuelsis defined by the following equation:

A T (test fuel) A T (tetralin) A T (isooctane) A T (tetralin) LuminOsityNO. X 100 AS'lM Standards on Petroleum Products and Lubricants,published 1956 by the American Society for Testing Materials.

temperature of the incoming air, the other shielded from the flame andinserted in the chimney to measure the temperature of the combustiongases. A radiometer is also adjustably positioned 'to measure the amountof radiation emanating from the flame.

To determine the luminosity number, several determinations are madeburning tetralin in the lamp, each run being made at a different Wickheight, the radiometer being positioned at the zone of maximum radiationand the amount of radiation for each determination and the temperaturedifferential between the incoming air and the combustion gases beingrecorded. After several determinations have been made on tetralin acurve is drawn plotting AT against the amount of radiation. Similarcurves are then made for isooctane and the test fuel. The AT for eachmaterial at a selected amount of radiation, e.g., 0.3 mv. is read fromthe curves and is inserted in the appropriate place in the aboveformula. The luminosity number of the test fuel is then easilycalculated.

Accordingly, the present invention contemplates a process for theproduction of a jet fuel of improved properties which comprises passingthe feed hydrocarbon in the liquid phase serially through a plurality ofreaction zones maintained at elevated temperatures and pressures, thepressure in each zone being at least 25 p.s.i.g. and preferably at least50 p.s.i.g. lower than the pressure of the preceding zone and recoveringthe fraction boiling from about 250600 F. or any selected portionthereof such as the BOO-480 P. fraction from the reaction product. Thepresent invention also contemplates an after-treatment for theproduction of superior fuels.

The process of the invention is carried out in the absence of acatalyst. In other words, the reaction zones are void and containneither catalyst nor packing. The reaction conditions such astemperature and pressure are maintained high enough to keepsubstantially all of the reactants in the liquid phase. Thus, at leastand preferably at least of each reaction zone will contain reactants inthe liquid phase. Temperatures will range from 770 to 930 F., preferably790 to 870 F. Pressures will range from 50 to 1000 p.s.i.g. or higher,the pressure in each reactor being lower than the pressure in thepreceding reactor. Normally, all of the reactors will be maintained atsubstantially the same temperature. Reaction times of 60 to 300 minutesmay be employed for the liquid material, preferably reaction times of 90(to 180 minutes 'are used. The ratio of liquid to vapor in the systemshould be maintained between about 18:1 and 180: 1.

Any suitable hydrocarbon material may be treated by the process of thepresent invention. Preferably, the feed stock has an initial boilingpoint above the desired end point of the product jet fuel. The chargestock may be a virgin distillate, a deasphalted reduced crude, adeasphalted furfural refined reduced crude or distillate, a furfuralrefined propane distillate prepared from a deasphalted reduced crude,paraflin wax or a mixture thereof. A particularly desirable jet fuel isproduced by topping crude, deasphalting the reduced crude, subjectingthe DA oil to a mild low conversion catalytic denaphthenizationtreatment, extracting the product with furfural, and subjecting the raflinate to the liquid phase thermal treatment described above.

The invention may be better understood from the following exampledescribed in connection with the accompanying drawing which showsdiagrammatically a flow scheme for the practice of the presentinvention.

The feed, which in this case is a rafiinate fraction obtained bysubjecting a deasphalted oil to a mild catalytic denaphthenization at atemperature of 750 F., atmospheric pressure, a space velocity of 1.0volume of feed per volume of catalyst per hour using a silica-aluminaPatented Sept. 8, 1964 spanner;

bead catalyst and extracting the product with furfural, and which has aninitial boiling point of 550 F., is introduced through line 21, passesthrough heat exchanger 22, line 23, heat exchanger and line 26 to heater27 where it is heated to a reaction temperature of 850 F. The feed thenpasses through transfer line 28 to reactor 29 which is maintained at apressure of 400 p.s.i.g. The feed is then removed from the bottom ofreactor 29 and sent through lines 38 and 30 to reactor 31, which ismaintained at a temperature of 860 F. and a pressure of 300 p.s.i.g. Inthe upper portion of reactor 31 where a vapor space is maintained andinto which the feed from line 30 is introduced, the vapors aredisengaged from the incoming liquid and removed through line 33. Theliquid passes downwardly through reactor 31 and by means of lines 32 and35 is introduced into the upper portion of reactor 36 which ismaintained at a temperature of 870 F. and a pressure of 150 p.s.i.g.Vaporous material disengaged from the liquid is removed from the upperportion of reactor 36 by means of line 37 and the liquid material iswithdrawn through lines 39 and 40 and introduced into the upper portionof reactor 42 which is maintained at a temperature of 880 F. and apressure of p.s.i.g. Vaporous material is removed from reactor 42through line 43 and the liquid material is removed from the lowerportion of reactor 42 and is sent by means of line 44, heat exchanger 25and line 46 to flash tower 47. In flash tower 47 material boilingthrough the gas oil range or up to about 800 F. is removed as overheadthrough line 43 and residual material is Withdrawn through line 50. Thislatter material is removed from the system through line 51. The overheadwithdrawn from flash tower 47' through line 48 is combined with thevapors and gaseous material in line 34 and is introduced into the lowerportion of fractionating tower 52. The fractionating tower 52 isoperated at essentially atmospheric pressure and the overhead withdrawnthrough line 53 has the end point of the desired jet fuel, which, inthis example, is 480 F. The overhead passes through condenser 54 andline 55 to separator 56 in which the non-condensibles are separated fromthe liquid and withdrawn through line 63. The liquid prodnot is removedfrom separator 56 through line 57 and sent through line 58 to afractionator (not shown) from which the desired jet fuel fraction iswithdrawn as bottoms. The product has a boiling range of 300480 F. and aluminosity number of 102.

To improve the separation of the desired product a portion of thematerial withdrawn from separator 56 through line 57 may be recycled tofractionating tower 52 through line 60.

The residue from fractionator 52 withdrawn through line 62 is passedthrough heat exchanger 22, line 64- and a portion may be withdrawn fromthe system through line 65. Another portion thereof after passingthrough heat exchanger 22. is recycled as reflux to flash tower 47through lines 64 and 66. Another portion of this residue may be divertedthrough line 7 0 and split into separate streams which are fed throughlines 71, '70 and 72, through heaters 80, 81 and 82 and then throughlines 84, 85 and 86 respectively to supply the heat necessary tomaintain the reactant stream at the desired reaction temperature andalso to subject this residual material to additional thermal treatment.When this last portion is recycled to extinction, no material will beWithdrawn through line 65. If desired, hydrogen and/or inert gas such asnitrogen, methane, natural gas may be introduced into the system throughline 89 and separated into streams which pass through lines 91, 89, 92,lines 71, 70, 72, heaters 80, 81, 82, lines 84, 85, 86, lines 30, 35, 40into reactors 31, 36 and 42 respectively. The gas so introduced into thesystem serves to maintain the reactant liquid at reaction temperatureand also serves to assist in disengaging vaporous material contained inthe liquid reactant. Hydrogen, in addition, serves to suppress the 4:formation of olefins and reduce their tendency to form high polymers.

It will be obvious to those skilled in the art that various devices suchas pumps, compressors, liquid level controls, pressure letdown valvesand the like have been omitted from the drawing for the sake ofsimplicity. For example, the operation of reactors 31, 36 and 42 is suchthat each reactor contains at least liquid and preferably liquidreactant. The vapor space is maintained by a liquid level control whichoperates valves (not shown) in lines 32, 39 and 46 in conjunction withpressure control valves (not shown) located in lines 33, 37 and 43.

For the production of superior fuels, i.e. fuels having luminositynumbers approaching or exceeding the product of the desired boilingrange may be further treated for the elimination of aromatichydrocarbons, particularly bicyclic aromatics.

One method for reducing the aromatic hydrocarbon content is to contactthe fuel with a hydrogenation catalyst such as nickel-kieselguhr at atemperature between about 500 and 675 F., a pressure between about 250and 750 p.s.i.g., a space velocity between about 0.2 and 10 v./v./ hr.and a hydrogen ratio of between about 5000 and 15,000 s.c.f./bbl. offeed. This treatment generally results in an increase of about 20 to 40in the luminosity number of the fuel. Advantageously, the product fraction boiling below the desired fraction, that is, the BP- 300 P.fraction, is subjected to catalytic reforming for conversion to a motorfuel of high octane number and the hydrogen produced by this treatmentis used for the hydrogenation of the desired fraction. In cases wherethe fuel has an undesirably high sulfur content a sulfactive catalystsuch as a nickel-tungstensulfide or cobaltmolybdenum oxide or sulfidecatalyst may be used.

Another suitable method for the elimination of aromatic compounds is totreat the fuel with a selective adsorbent such as silica gel or amolecular sieve. When the fuel is treated with silica gel, the aromatichydrocarbons are adsorbed and the resulting product is essentiallyparaffinic and isoparaffinic and free from aromatics. When the fuel istreated with a molecular sieve having a pore size of 5 A. the straightchain parafiins are adsorbed and the unadsorbed material is composedessentially of nonstraight chain hydrocarbons. Desorption of themolecular sieve using a desorbing agent such as hydrogen or lighthydrocarbons, for example, propane or butane, produces a fuelessentially paraffinic in nature and having a luminosity number of about150.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and therefore only such limitations should be imposed asare indicated in the appended claims.

I claim:

1. A process for the production of a jet fuel of high luminosity numberand a motor fuel of high octane number which comprises contacting ahydrocarbon oil with a denaphthenization catalyst underdenaphthenization conditions, extracting the product with furfural toproduce an extract phase and a raflinate phase, passing the rafiinatephase serially through a plurality of reaction zones at a temperaturebetween 770 and 930 F. and an,

elevated pressure not greater than about 1000 p.s.i.g., the pressure ineach reaction zone being at least 25 p.s.i. lower than the pressure inthe preceding reaction zone, removing vaporous material formed in eachreaction zone from the reactant stream prior to passing the reactantstream into the next down stream reaction zone whereby the hydrocarbonreactant introduced into each reaction zone is substantially completelyin the liquid phase, subjecting the liquid product stream to flashdistillation to remove material boiling through the gas oil range asoverhead from a residual fraction, combining said mate rial boilingthrough the gas oil range with said vaporous material said vaporousmaterial having been maintained apart from the liquid reactant streamafter separation therefrom, subjecting the combined stream to fractionaldistillation, removing as liquid bottoms from said fractionaldistillation material boiling above about 500 F., separating theoverhead from said fractional distillation into a light liquid fractionboiling up to about 300 F. and a heavy fraction boiling from about300-500 F., contacting the light fraction with a reforming catalystunder reforming conditions with the concomitant production of hydrogento produce a motor fuel of high octane number, contacting the heavyfraction with a hydrogenation catalyst under hydrogenation conditions toreduce the aromatic content thereof in the presence of hydrogen producedby the reforming reaction to produce a jet fuel of high luminositynumber.

2. The process of claim 1 in which a heated gas is introduced into thereactant stream with said heated stream.

3. The process of claim 2 in which the gas is hydrogen.

4. The process of claim 1 in which a portion of the bottoms removed fromthe fractional distillation zone is recycled to the flash distillationzone.

5. A process for the production of a jet fuel of high luminosity numberand a motor fuel of high octane number which comprises contacting ahydrocarbon oil with a denaphthenization catalyst at a temperature ofabout 750 F. atmospheric pressure, a space velocity of about volume offeed per volurne of catalyst per hour, extracting the product withfurfural to produce an extract phase and a raffinate phase, passing therafiinate phase in the liquid phase into a first reaction zonemaintained at a temperature of about 850 F. and a pressure of about 400p.s.i.g., removing the reactant stream from said first reaction zone,reducing the pressure on said reactant stream to about 300 psig. todisengage vaporous material from the liquid material, separating thevaporous material from the liquid material, passing the liquid materialto a second reaction zone maintained at a temperature of about 860 F.and a pressure of about 300 p.s.i.g., withdrawing the reactant streamfrom said second reaction zone, reducing the pressure on the reactantstream to about 150 p.s.i.g. to disengage vaporous material from liquidmaterial, separating the vaporous material from the liquid material andpassing the liquid to a third reaction zone maintained at a temperatureof about 870 F. and a pressure of about 150 p.s.i.g., withdrawingreactant stream from the said third reaction zone, reducing the pressureon the reactant stream to about 50 p.s.i.g. to disengage vaporousmaterial from the liquid material,

separating the vaporous material from the liquid, passing the liquidthrough a fourth reaction zone maintained at a temperature of about 880F. and a pressure of about p.s.i.g., the contents of each reaction zonebeing substantially completely in the liquid phase, withdrawing theliquid material from said fourth reaction zone, subjecting the withdrawnliquid to flash distillation, removing as overhead from said flashdistillation material having a distillation end point of about 800 F.,combining the overhead from said flash distillation with the streams ofvaporous material removed from the reaction zones as aforesaid, saidvaporous material having been maintained apart from the liquid reactantstream after separation therefrom, subjecting the combined stream to afractional distillation, removing as liquid bottoms from said fractionaldistillation material boiling above about 500 F., heating a portion ofthe bottoms removed from said fractional distillation zone, separatingthe heated portions into a plurality of streams and introducing each ofsaid streams into the reactant stream as the reactant passes from onereaction zone to the next, separating the overhead from said fractionaldistillation zone into a light liquid fraction boiling up to 300 F. anda heavy fraction boiling from about 300500 F., contacting the lightfraction with a reforming catalyst under reforming conditions with theconcomitant production of hydrogen to produce a motor fuel of highoctane number, contacting the heavy fraction with a hydrogenationcatalyst under hydrogenation conditions to reduce the aromatic contentthereof in the presence of hydrogen produced by the reforming reactionto produce a jet fuel of high luminosity number.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Conversion of Petroleum, Sachanen, Reinhold Co., New York,1940, pages 122 and 123.

Chemical Technology of Petroleum, by Gruse et al., page 402, McGraW-HillBook Co., New York, 1942.

Jet Fuels, Gas & Oil Journal, October 6, 1952, pages 96 to 98.

Pub.

1. A PROCESS FOR THE PRODUCTION OF A JET FUEL OF HIGH LUMINOSITY NUMBERAND A MOTOR FUEL OF HIGH OCTANE NUMBER WHICH COMPRISES CONTACTING AHYDROCARBON OIL WITH A DENAPHTHENIZATION CATALYST UNDERDENAPHTHENIZATION CONDITIONS, EXTRACTING THE PRODUCT WITH FURFURAL TOPRODUCE AN EXTRACT PHASE AND A RAFFINATE PHASE, PASSING THE RAFFINATEPHASE SERIALLY THROUGH A PLURALITY OF REACTION ZONES AT A TEMPERATUREBETWEEN 770 AND 930*F. AND AN ELEVATED PRESSURE NOT GREATER THAN ABOUT1000 P.S.I.G., THE LOWER THAN THE PRESSURE IN THE PRECEDING REACTIONZONE, REMOVING VAPOROUS MATERIAL FORMED IN EACH REACTION ZONE FROM THEREACTANT STREAM PRIOR TO PASSING THE REACTANT STREAM INTO THE NEXT DOWNSTREAM REACTION ZONE WHEREBY THE HYDROCARBON REACTANT INTRODUCED INTOEACH REACTION ZONE IS SUBSTANTIALLY COMPLETELY IN THE LIQUID PHASE,SUBJECTING THE LIQUID PRODUCT STREAM TO FLASH DISTILLATION TO REMOVEMATERIAL BOILING THROUGH THE GAS OIL RANGE AS OVERHEAD FROM A RESIDUALFRACTION, COMBINING SAID MATERIAL BOILING THROUGH THE GAS OIL RANGE WITHSAID VAPOROUS MATERIAL SAID VAPOROUS MATERIAL HAVING BEEN MAINTAINEDAPART FROM THE LIQUID REACTANT STREAM AFTER SEPARATION THEREFROM,SUBJECTING THE COMBINED STREAM TO FRACTIONAL DISTILLATION, REMOVING ASLIQUID BOTTOMS FROM SAID FRACTIONAL DISTILLATION MATERIAL BOILING ABOVEABOUT 500*F., SEPARATING THE OVERHEAD FROM SAID FRACTIONAL DISTILLATIONINTO A LIGHT LIQUID FRACTION BOILING UP TO ABOUT 300*F., CONTACTING THELIGHT FRACTION WITH A REFORMING CATALYST UNDER REFORMING CONDITIONS WTHTHE CONCOMITANT PRODUCTION OF HYDROGEN TO PRODUCE A MOTOR FUEL OF HIGHOCTANE NUMBER, CONTACTING THE HEAVY FRACTION WITH A HYDROGENATIONCATALYST UNDER HYDROGENATION CONDITIONS TO REDUCE THE AROMATIC CONTENTTHEREOF IN THE PRESENCE OF HYDROGEN PRODUCED BY THE REFORMING REACTIONTO PRODUCE A JET FUEL OF HIGH LUMINOSITY NUMBER.